The present invention is concerned with the manufacture of 3,7,11-trimethyldodeca-2,4,6,10-tetraen-1-yl-phosphonium salts and of lycopene and with novel 3,7,11-trimethyldodeca-2,4,6,10-tetraen-1-yl-phosphonium salts in this process.
Lycopene is a natural red carotinoid which occurs e.g. in tomatoes.
Carotinoids are manufactured mainly by a Wittig reaction from phosphonium salts and aldehydes. The phosphonium salts which are used are salts of strong acids-usually halides, sulphates or phosphates-and are obtained as a rule from the corresponding alcohols, halides etc. However, the manufacture of lycopene according to this method gives only low yields, with especially in the production of the phosphonium salts predominantly unreactive byproducts being formed.
It has now been found that 3,7,11-trimethyldodeca-2,4,6,10-tetraen-1-yl-phosphonium alkanoates and -phosphonium hydroxytrifluoroborates can be manufactured in high yield and that these can be reacted further in a Wittig reaction just as the usual phosphonium salts of strong acids. If desired, the alkanoates and hydroxytrifluoroborates can be converted, prior to the conversion into lycopene, in a simple manner into the phosphonium salts of usual strong acids, whereby the latter can be obtained via the alkanoates and hydroxytrifluoroborates in substantially higher yield.